Emergency management of meningitis

A febrile illness is a common reason for both adults and children to attend an accident and emergency department. The identi®cation of the one patient with meningitis out of many with trivial viral infections remains a dif®cult task. Even once the diagnosis is made clinically, the subsequent investigation and management of the patient remains controversial, with opinions often in¯uenced by one or two adverse experiences. In this review, we discuss the diagnostic and management issues relevant to the emergency care specialist, paediatrician or physician faced with such patients. The detailed immediate care of patients requiring respiratory and cardiovascular support, particularly those with associated septicaemic shock, has been reviewed elsewhere 1. It has been suggested that bacterial meningitis presents in two formsЮrst, an acute presentation with a history of less than 24 hours which is associated with a poor outcome; secondly, a more insidious form which is dif®cult to detect but has a better outcome 2. Few doctors would want to miss the opportunity to interrupt the pathogenic process at an early stage. Thus when considering bacterial meningitis, it is helpful to understand the essential pathogenic processes that mediate this disease 3. In most cases the organisms cross the meninges from the bloodstream in the course of a bacteraemic illness. Patients with non-speci®c signs and symptoms may be bacteraemic with only limited passage of organisms across the blood±brain barrier (BBB); therefore the classic signs of meningitis may be absent (see below). Features of meningism become more prominent once bacterial invasion across the BBB is established. The release of bacterial toxins such as endotoxin, peptidoglycan and teichoic acid initiates an in¯ammatory process that leads to impairment of BBB function, cerebral oedema and raised intracranial pressure. Increased leukocyte traf®c across the blood vessel wall triggers cerebral vascular thrombosis. The combination of globally reduced cerebral blood-¯ow and focal ischaemia results in neuronal injury and cerebral damage which manifest clinically as coma, seizures and focal neurological signs. It is therefore important to appreciate that, while the characteristic featuresÐfever, headache, vomiting, and signs of meningeal irritation, with or without a petechial rashÐare easy to recognize, the signs of meningitis in its early stages are often non-speci®c and require a high index of suspicion 4,5. Fever may be absent initially in up to 30% of individuals with bacterial meningitis 6. Between 20% and 30% of patients with meningitis do not have signs of meningism at presentation, particularly …